What Limits the Performance of Ta3N5 for Solar Water Splitting?

Overview

Title: 

What Limits the Performance of Ta3N5 for Solar Water Splitting?

Abstract: 

Tantalum nitride (Ta3N5) is a promising photoelectrode for solar water splitting. Although near-theoretical-limit photocurrent has already been reported on Ta3N5, its low photovoltage and poor stability remain critical challenges. In this study, we used Ta3N5 nanotubes as a platform to understand the origins of these issues. Through a combination of photoelectrochemical and high-resolution electron microscope measurements, we found that the self-limiting surface oxidation of Ta3N5 resulted in a thin amorphous layer (ca. 3 nm), which proved to be effective in pinning the surface Fermi levels and thus fully suppressed the photoactivity of Ta3N5. X-ray core-level spectroscopy characterization not only confirmed the surface composition change resulting from the oxidation but also revealed a Fermi-level shift toward the positive direction by up to 0.5 V. The photoactivity degradation mechanism reported here is likely to find applications in other solar-to-chemical energy-conversion systems.

Authors: 

He, Yumin; Thorne, James E.; Wu, Cheng Hao; Ma, Peiyan; Du, Chun; Dong, Qi; Guo, Jinghua; Wang, Dunwei

DOI: 

Journal: 

Chem

Year: 

2016

Catalysis

Catalysis: 

Indicate the type of catalyst: 

Catalyst Name/Chemical Formula: 

  • Tantalum Nitride (Ta3N5)

Catalyst Keyword(s): 

Tantalum Nitride

Description of catalysis: 

Reaction type: 

Reactants: 

Reactant: 

Products: 

Product: 

Solvent(s): 

pH: 

13.60

Proposed mechanism: 

Duration of experiment: 

3.00
hours (hr)

Measured Stability: 

1.00
minutes (m)

Observed decrease in stability: 

Yes

Regenerative?: 

No

Surface Area Enhancement: 

Referenced to Fc+/Fc?: 

No

Is a proton source used?: 

No

Is Bulk Electrolysis reported?: 

No

Active Wavelength Range: 

Unit: 

ASTM Illumination Conditions: 

No

Is the system PV-driven?: 

No

Active Wavelength Range: 

Unit: 

Catalyst and photoactive species are the same: 

Yes

Is the photoactive species molecular?: 

No

Anode Material Photoactive: 

Cathode Material Photoactive: 

Deposition Process: 

ASTM Illumination Conditions: 

No

Illumination Source: 

Power: 

100.00
mW/cm2

Filter: 

Photocurrent: 

1.50
mA/cm2

Onset Potential for Photocurrent: 

0.60
V

Stability of Photocurrent: 

1.00
minutes (m)

Applied Voltage: 

1.23
V

Reference Electrode: 

Keywords: 

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